catalyzes the reversible condensation of cyanide with 4-hydroxybenzaldehyde to yield 4-hydroxymandelonitrile; can be obtained from plant extracts by immobilized metal ion affinity chromatography; does not accept aliphatic hydroxynitriles, unlike EC 4.1.2.10 mandelonitrile lyase and EC 4.1.2.39 hydroxynitrilas